/**
 * Tag-closer extension for CodeMirror.
 *
 * This extension adds a "closeTag" utility function that can be used with key bindings to
 * insert a matching end tag after the ">" character of a start tag has been typed.  It can
 * also complete "</" if a matching start tag is found.  It will correctly ignore signal
 * characters for empty tags, comments, CDATA, etc.
 *
 * The function depends on internal parser state to identify tags.  It is compatible with the
 * following CodeMirror modes and will ignore all others:
 * - htmlmixed
 * - xml
 *
 * See demos/closetag.html for a usage example.
 *
 * @author Nathan Williams <nathan@nlwillia.net>
 * Contributed under the same license terms as CodeMirror.
 */
(function () {
    /** Option that allows tag closing behavior to be toggled.  Default is true. */
    CodeMirror.defaults['closeTagEnabled'] = true;

    /** Array of tag names to add indentation after the start tag for.  Default is the list of block-level html tags. */
    CodeMirror.defaults['closeTagIndent'] = ['applet', 'blockquote', 'body', 'button', 'div', 'dl', 'fieldset', 'form', 'frameset', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'head', 'html', 'iframe', 'layer', 'legend', 'object', 'ol', 'p', 'select', 'table', 'ul'];

    /** Array of tag names where an end tag is forbidden. */
    CodeMirror.defaults['closeTagVoid'] = ['area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input', 'keygen', 'link', 'meta', 'param', 'source', 'track', 'wbr'];

    function innerState(cm, state) {
        return CodeMirror.innerMode(cm.getMode(), state).state;
    }


    /**
     * Call during key processing to close tags.  Handles the key event if the tag is closed, otherwise throws CodeMirror.Pass.
     * - cm: The editor instance.
     * - ch: The character being processed.
     * - indent: Optional.  An array of tag names to indent when closing.  Omit or pass true to use the default indentation tag list defined in the 'closeTagIndent' option.
     *   Pass false to disable indentation.  Pass an array to override the default list of tag names.
     * - vd: Optional.  An array of tag names that should not be closed.  Omit to use the default void (end tag forbidden) tag list defined in the 'closeTagVoid' option.  Ignored in xml mode.
     */
    CodeMirror.defineExtension("closeTag", function (cm, ch, indent, vd) {
        if (!cm.getOption('closeTagEnabled')) {
            throw CodeMirror.Pass;
        }

        /*
         * Relevant structure of token:
         *
         * htmlmixed
         * 		className
         * 		state
         * 			htmlState
         * 				type
         *				tagName
         * 				context
         * 					tagName
         * 			mode
         *
         * xml
         * 		className
         * 		state
         * 			tagName
         * 			type
         */

        var pos = cm.getCursor();
        var tok = cm.getTokenAt(pos);
        var state = innerState(cm, tok.state);

        if (state) {

            if (ch == '>') {
                var type = state.type;

                if (tok.className == 'tag' && type == 'closeTag') {
                    throw CodeMirror.Pass; // Don't process the '>' at the end of an end-tag.
                }

                cm.replaceSelection('>'); // Mode state won't update until we finish the tag.
                pos = {line: pos.line, ch: pos.ch + 1};
                cm.setCursor(pos);

                tok = cm.getTokenAt(cm.getCursor());
                state = innerState(cm, tok.state);
                if (!state) throw CodeMirror.Pass;
                var type = state.type;

                if (tok.className == 'tag' && type != 'selfcloseTag') {
                    var tagName = state.tagName;
                    if (tagName.length > 0 && shouldClose(cm, vd, tagName)) {
                        insertEndTag(cm, indent, pos, tagName);
                    }
                    return;
                }

                // Undo the '>' insert and allow cm to handle the key instead.
                cm.setSelection({line: pos.line, ch: pos.ch - 1}, pos);
                cm.replaceSelection("");

            } else if (ch == '/') {
                if (tok.className == 'tag' && tok.string == '<') {
                    var ctx = state.context, tagName = ctx ? ctx.tagName : '';
                    if (tagName.length > 0) {
                        completeEndTag(cm, pos, tagName);
                        return;
                    }
                }
            }

        }

        throw CodeMirror.Pass; // Bubble if not handled
    });

    function insertEndTag(cm, indent, pos, tagName) {
        if (shouldIndent(cm, indent, tagName)) {
            cm.replaceSelection('\n\n</' + tagName + '>', 'end');
            cm.indentLine(pos.line + 1);
            cm.indentLine(pos.line + 2);
            cm.setCursor({line: pos.line + 1, ch: cm.getLine(pos.line + 1).length});
        } else {
            cm.replaceSelection('</' + tagName + '>');
            cm.setCursor(pos);
        }
    }

    function shouldIndent(cm, indent, tagName) {
        if (typeof indent == 'undefined' || indent == null || indent == true) {
            indent = cm.getOption('closeTagIndent');
        }
        if (!indent) {
            indent = [];
        }
        return indexOf(indent, tagName.toLowerCase()) != -1;
    }

    function shouldClose(cm, vd, tagName) {
        if (cm.getOption('mode') == 'xml') {
            return true; // always close xml tags
        }
        if (typeof vd == 'undefined' || vd == null) {
            vd = cm.getOption('closeTagVoid');
        }
        if (!vd) {
            vd = [];
        }
        return indexOf(vd, tagName.toLowerCase()) == -1;
    }

    // C&P from codemirror.js...would be nice if this were visible to utilities.
    function indexOf(collection, elt) {
        if (collection.indexOf) return collection.indexOf(elt);
        for (var i = 0, e = collection.length; i < e; ++i)
            if (collection[i] == elt) return i;
        return -1;
    }

    function completeEndTag(cm, pos, tagName) {
        cm.replaceSelection('/' + tagName + '>');
        cm.setCursor({line: pos.line, ch: pos.ch + tagName.length + 2});
    }

})();
